Can I enter Canterbury-Bankstown LGA if I don't live there?

The point of the restrictions is to reduce mobility and thus reduce the risk of transmission between people.

While it's not really within the spirit of the "stay at home" orders - I don't really have a problem with someone travelling less than 5km to work on an unoccupied house, alone.

Provided that they aren't just "popping out to the shops" to get a coffee or food while they are working there.

And if you need to visit a Bunnings or similar to get supplies - then I think you are definitely stretching the rules.

Ask yourself: are your activities increasing the risk to you or others compared to if you remained at home? If yes - because you are interacting with more people than otherwise - then don't do it.

Also - be prepared for a visit from the police if your neighbours take issue with renovations being undertaken while everyone is in lockdown. I don't know how the police will interpret your actions.